Re: [SLUG] BASH command return value
On Fri, Aug 04, 2000 at 11:31:13AM -0400, Subba Rao wrote: > In this case, when my command fails the BASH variable $? value is displayed > in my prompt. What is happening is that a command return value stays there > until an new command is issued. A newline for the shell will still return the > previous $? value. $? value is never reset until a new command is issued. Well, that's just the way shells work. When you write a shell script, you never care whether you put a few blank lines between the command that you're testing. Now, as you've found, you can override that behaviour by executing a command that returns true (0) _after_ the $? value has been displayed, but before the next command is accepted. You chose whois, but that's a real executable, so you have to fork an extra time for each prompt. If you use a shell builtin like $(exit 0), to reset the result value, and keep using \u for your user name, then (a) your shell might run a bit more quickly, but (b) you can't actually use $? yourself, on the command line. Well you can in multi-statement lines, I guess. Aesthetics aside, better to have learned this lesson, leave the prompt as you originally had it (not resetting the result), and reset it manually if you feel strongly about it. It actually sounds like a bloody good idea. Think I'll try it myself for a while. Thanks, -- Andrew -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://slug.org.au/lists/listinfo/slug
Re: [SLUG] BASH command return value
> When I change the PS1 sring to, > > PS1='($?)`whoami`@\h:\w =>' > > The return value for $? is immediately displayed in the next prompt. > > (0)subb3@myhost:~ => > (0)subb3@myhost:~ => lssdfh > (258)subb3@myhost:~ => > (0)subb3@myhost:~ => > (0)subb3@myhost:~ => ls > > (0)subb3@myhost:~ => ls o > ls: o: No such file or directory > (1)subb3@myhost:~ => > > In BASH, why does the "\u" and "whoami" make a big difference for the $? > value in > PS1 string? The BASH version is 2.04. Because you are running a whoami command inside the prompt? To convince yourself that the next number displayed is the result of the command inside the `s, substitute exit 123 for whoami. -- This mail sent via NLC WebMail: http://www.nlc.net.au/ -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://slug.org.au/lists/listinfo/slug
[SLUG] BASH command return value
My PS1 prompt has the following string, PS1='($?)\u@\h:\w =>' In this case, when my command fails the BASH variable $? value is displayed in my prompt. What is happening is that a command return value stays there until an new command is issued. A newline for the shell will still return the previous $? value. $? value is never reset until a new command is issued. (0)subb3@myhost:~ => (0)subb3@myhost:~ => lssdfh <== This is no command (258)subb3@myhost:~ => (258)subb3@myhost:~ => (258)subb3@myhost:~ => (258)subb3@myhost:~ => ls (0)subb3@myhost:~ => When I change the PS1 sring to, PS1='($?)`whoami`@\h:\w =>' The return value for $? is immediately displayed in the next prompt. (0)subb3@myhost:~ => (0)subb3@myhost:~ => lssdfh (258)subb3@myhost:~ => (0)subb3@myhost:~ => (0)subb3@myhost:~ => ls (0)subb3@myhost:~ => ls o ls: o: No such file or directory (1)subb3@myhost:~ => In BASH, why does the "\u" and "whoami" make a big difference for the $? value in PS1 string? The BASH version is 2.04. -- Subba Rao [EMAIL PROTECTED] http://pws.prserv.net/truemax/ => Time is relative. Here is a new way to look at time. <= http://www.smcinnovations.com -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://slug.org.au/lists/listinfo/slug
